The present invention relates to a device for extending distances of projectiles shot from a gun and to a method for increasing distance traversed by a projectile shot from a gun.
Guns are made in a variety of different sizes utilizing a variety of different propellants. Guns are comprised generally of a main body that includes a barrel closeable at one end by a sliding block, known as a breach block or a screw. The breach block defines a chamber for receipt of a propellant charge such as a bullet or a paint ball charge. Extending from the chamber is a tapered transition region to the barrel.
In one embodiment, the barrel, which includes an inner radial surface, is provided with spiral grooves on the inner radial surface. These spiral grooves are also known as "rifles." The rifles also called "rifling" impart a spinning motion to the projectile. Rifling is typically at a pitch which is expressed as a multiple of a bore diameter defined by the barrel. For instance, the pitch may be forty times the bore, which means that the projectile performs one revolution about its longitudinal axis over a distance equal to forty times the bore diameter of the barrel.
When the gun is loaded, a soft metal driving band at one end of the projectile is pressed into the rifling grooves, thereby centering the projectile in the barrel. When the gun is fired, a firing pin strikes a primer. This action ignites the charge which may be either enclosed in a cartridge, or entirely separate from the projectile. Explosive powder in the charge burns extremely rapidly and develops a very high gas pressure in the chamber, on the order of 45,000 psi. When the gas pressure exceeds the pressure with which the driving band is gripped in the rifling, the projectile is set in motion so that the space behind the projectile increases in volume as the gas expands. After an initial pressure builds up in the chamber, there is a drop in pressure as the projectile travels along the barrel. At the instant the projectile leaves the muzzle of the gun, the gas still has a high pressure which causes the report when the gas escapes into the atmosphere.
Gas pressure developed when the gun is fired produces high stresses, particularly in the interior of the barrel. Because of these high stresses, one piece barrels, called "mono-block" barrels, are used principally for guns of relatively small caliber. Medium and large caliber guns are barrels of a composite construction.
In a firing position, the breach block is locked against the force of any exploding charge. In addition to a mechanism for moving the block, the breach block also includes a firing pin and an extraction system for removing the spent cartridge case when the breach block is opened after the gun has been fired.
Typically in a gun, the expulsion of the projectile is accompanied by a recoil movement of the barrel. Hydraulic breaking cylinders may be used to arrest this movement. A piston rod attached to the barrel pulls the piston back when the barrel recoils so that hydraulic fluid behind the piston is forced through narrow passages into a space in front of the piston, thereby producing a breaking effect.
This general type of gun device has been used to project everything from bullets to paint balls. Several patents are directed specifically to paint ball guns. The Gardner patent, U.S. Pat. No. 5,228,427, describes an improved barrel for a paint ball gun. The barrel includes a number of radial holes drilled in a spiral pattern in order to cause the paint ball to spin around its longitudinal axis in flight. The Gardner patent describes the paint ball as stabilized in flight by imparting angular momentum to the ball about its longitudinal axis. No aerodynamic effect is described.
The Slonaker et al. patent, U.S. Pat. No. 5,640,945, issuing Jun. 24, 1997, describes a paint ball and gun that improve the range and accuracy of paint ball projections. The paint ball includes an external surface contoured to increase frictional interaction with air. The barrel and paint ball gun interact so that a significant back spin is imparted to the ball. The interaction includes a plurality of closed internal recesses and open internal recesses. The open internal recesses are vented to the atmosphere.